1. Field of the Invention
The present invention relates to a method for extracting the effective ingredients from dried plant materials such as coffee, black tea, green tea, herbs, and the like as a concentrated liquid, and to a device for implementing that method.
2. Description of the Prior Art
Conventionally, the most basic method for extracting the effective ingredients from dried plant materials such as coffee, black tea, green tea, herbs, and the like as a beverage involves adding boiling water to the pulverized dried plant materials and digesting, followed by filtration of the digested material. At the present time, this method is commonly used both industrially and in the home. In addition, there are also many cases in which this method is employed on a large scale for large volume production in a factory in order to market the extracted liquid as a canned or bottled beverage.
Among the dried plant materials such as black tea, green tea, and herbs there are no great differences in the use of this extraction method. However, various different types of methods have been conventionally used for extraction of coffee. Specifically, these extraction methods/or coffee may be broadly classified into extraction using water at high temperature as outlined above, and extraction using water at normal temperature.
Commonly known methods for extraction using water at normal temperature include a water drip system and a Dutch system. The methods using water at normal temperature cause no deterioration in the raw material. A liquid coffee can be obtained with an amber color of high clarity while at the same time maintaining a superior flavor and odor without loss of the unique fragrance of coffee. However, there is a major drawback inasmuch as the extraction takes a long time, normally ranging from five hours to about fifteen hours. In particular, this method is not suitable for large volume production as used industrially. Also, in order to sell the product as a beverage it must be sterilized to prevent decomposition resulting from preservability problems.
On the other hand, commonly known methods for extraction of liquid coffee using water at high temperature include a jet system, a syphon system, a drip system, a decoction system, and the like, These methods make short-time extraction possible, but because of changes in the raw material caused by the high temperatures there is a tendency toward loss of the unique fragrance of coffee and for production of turbidity in the liquid coffee resulting from the extraction of albumin, and an increase in the unpleasant bitter or astringent taste resulting from the extraction of tannin, such as chlorogenic acid, caffeic acid, and quinic acid.